It hasn’t been long since the Boston Celtics went into rebuild mode. In 2013, they traded their veteran core that won them the 2008 Larry O'Brien trophy and started all over again with a new coach.

Four years later, they were in contention for the Eastern Conference title. Now, entering their fifth year after starting the drastic process, the Celtics are ready to contend for the NBA championship.

Doc Rivers left that rebuilding Boston squad four years ago and now that the team is back atop the East, he can’t do anything but marvel with what happened after just a short amount of time.

Talking to the Boston Herald (via Stephen Hewitt), Rivers admitted he misses Boston and although he claimed that he doesn’t regret his decision to leave them for the LA Clippers, he shared the rebuilding the C’s did was the best he’s “ever seen” in any sport.

“My love for them hasn’t changed,” Rivers said of the Celtics. “For me, it was time for me to change. When you’re somewhere for nine years, you don’t think whether it’s the right or wrong decision, you think it’s the right decision for you at that time. But as far as wanting them to do well, that will never change. Unless they’re playing me.

“Other than that, love Danny (Ainge), love (owner Steve Pagliuca), that whole group, and I just want them to do well. I really do. I love what they’ve done. I think the turnaround in four years starting with hiring Brad and then going from … (Ainge) and (assistant general manager) Mike Zarren have done the best job I’ve seen in sports in a long, long time of rebuilding. Maybe ever.”

Rivers opted to leave Boston because he didn’t want to be part of the Celtics’ plan, so it’s difficult to imagine there isn’t even an inch of regret on his part, especially with the fact that he and the Clips have never been past the second round since he took the reins.

However, it’s unlikely Boston would find the success they had if Rivers is still at the helm.

Celtics head man Danny Ainge did well in trading Kevin Garnett and Paul Pierce to acquire Brooklyn’s first-round picks and more assets. Nevertheless, his decision to hire Brad Stevens as head coach out of Butler was one of the best moves he made as the 40-year-old established himself as one of the best minds in the league.